Preload images issue

[paquitoz]

Hello,

I've some javascript code which preload the images for a photo gallery made of clickable thumbnails and the images to be shown. The script is structured to preload the images in order to have a smooth experience while browsing through the thumbnails but, as the images are needed in quite high quality and can't be compressed any further, the page is too slow to load.

Basically, as the script sits between the head tags at the beginning of the page, it holds the loading of the whole page, leaving the user with a black page for a good 10 seconds on a fast connection.

Is there any chance I can preload the images in such a way I don't have to hold the whole page from displaying while the images are loaded? It would be ideal to be able to display the contents of the page (logo, menu, 1st picture of the gallery and foot of the page) while the images preload in the background.

Could please anybody help with this?

Here is the code I'm using:


<SCRIPT language=JavaScript1.1>
var myimages=new Array()
function preloadimages(){
for (i=0;i<preloadimages.arguments.length;i++){
myimages=new Image()
myimages.src=preloadimages.arguments
}
}
preloadimages("images/gallery/editorial/1.jpg","images/gallery/editorial/2.jpg","images/gallery/editorial/3.jpg","images/gallery/editorial/4.jpg","images/gallery/editorial/5.jpg","images/gallery/editorial/6.jpg","images/gallery/editorial/7.jpg","images/gallery/editorial/8.jpg","images/gallery/editorial/9.jpg","images/gallery/editorial/10.jpg","images/gallery/editorial/11.jpg","images/gallery/editorial/12.jpg","images/gallery/editorial/13.jpg","images/gallery/editorial/14.jpg","images/gallery/editorial/15.jpg","images/gallery/editorial/16.jpg","images/gallery/editorial/17.jpg","images/gallery/editorial/18.jpg","images/gallery/editorial/19.jpg","images/gallery/editorial/20.jpg","images/gallery/editorial/21.jpg","images/gallery/editorial/22.jpg","images/gallery/editorial/23.jpg","images/gallery/editorial/24.jpg","images/gallery/editorial/25.jpg")
function MM_swapImgRestore() { //v3.0
var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a)&&x.oSrc;i++) x.src=x.oSrc;
}
function MM_preloadImages() { //v3.0
var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
if (a.indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a;}}
}

function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers.document);
if(!x && d.getElementById) x=d.getElementById; return x;
}

function MM_swapImage() { //v3.0
var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
if ((x=MM_findObj(a))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
</SCRIPT>


and this is for the thumbnails:

<a onmousedown='changeimage(myimages[0],this.href)'><img src="images/gallery/thumb1.gif" alt="1" width="16" height="16" border="0" /></a>
<a onmousedown='changeimage(myimages[1],this.href)'><img src="images/gallery/thumb2.gif" alt="2" width="16" height="16" border="0" /></a>
<a onmousedown='changeimage(myimages[2],this.href)'><img src="images/gallery/thumb3.gif" alt="3" width="16" height="16" border="0" /></a>
<a onmousedown='changeimage(myimages[3],this.href)'><img src="images/gallery/thumb4.gif" alt="4" width="16" height="16" border="0" /><br />
</a> etc....


Any help would be much appreciated.

Thanks
paolo

 

[BillyRayPreachersSon]

Perhaps I'm missing something, but why not simply move your call to 'preloadimages' to a point in the source you're happy with them to start loading?

Dan



Coedit Limited - Delivering standards compliant, accessible web solutions

Dan's Page [blue]@[/blue] Code Couch:

http://www.codecouch.com/dan/

Code Couch Tech Snippets & Info:

http://www.codecouch.com/

 

[paquitoz]

Hi Dan,

Yours is a good observation, but I thought javascript could only sit between the <head></head> tags? I might be wrong on that.

Thanks
paolo

 

[BillyRayPreachersSon]

You are wrong on that.

Dan



Coedit Limited - Delivering standards compliant, accessible web solutions

Dan's Page [blue]@[/blue] Code Couch:

http://www.codecouch.com/dan/

Code Couch Tech Snippets & Info:

http://www.codecouch.com/

 

[feherke]

Hi

Paolo, you may find this Yahoo! Developer Network article interesting : Best Practices for Speeding Up Your Web Site | Put Scripts at the Bottom.

Feherke.

http://free.rootshell.be/~feherke/